Balancing machine



Jan. 7, 1936. A F MQYER ET AL Re. 19,812

BALANC I NG MACH INE original Filed May 2. 1924 4 Sheets-sheet 1 Jan. 7,1936.

A. F. MOYER ET AL BALANC ING MACHI NE original Filed May 2, 194

4 Sheets-Sheet 2 Jan. 7, 1936. A |=l MOYER Er AL Re. 19,812

BALANCING MACHINE Original Filed May 2, 1924 4 Sheets-Sheet 3 um@ B;

Jan. 7, 1936. A. F. MoYER l-:r AL Re. 19,812

BALANCuING MACHINE Original Filed May 2, 1924 4 Sheets-Sheet 4 ReissuedJan. 7, 1936 Re,

19,812 BALANCING MACHINE Amos F. Moyer, Minneapolis, Minn., and FrancisT. McDonough, deceased, late of Madison, Wis., by Precision BalancingMachine Company, Eau Claire, Wi., assignee, by mesne assignmentsOriginal No. 1,812,353, dated June 30, 1931, Serial No. 710,595, May 2,1924. Renewed October 21, 1927. Application for reissue February 5,1932, Serial No. 590,999S

' 2s claims. (c1. 73-51) The balancing machine of our invention and of abase on which is pivotally mounted a recshown herewith is oi' a typeadapted to make tangular frame or supporting means capable ofdetermination of unbalance to be corrected by oscillation under springrestraint. At one end oi application or removal of weight at determinatesaid frame is a headstock carrying a ball bearing angular positions ineach of two arbitrarily se- 'ily wheel and correction disk, whileintervening lected planes of the work, establishing thereby between saidheadstock, and the pivotal support complete dynamic balance, includingstatic balis a cross member with the two adjustable ball ance.Disclosures are herein made which would bearing rollers to support theadjacent end o1'. be equally applicable to balancing machines in thework. Beyond said pivots is a similar cross which static balance isestablished prior to demember with adjustable rollers to support the 10terminlng dynamic unbalance. Likewise, the overhanging end of the work.All of these memmachine of our invention is of the type in which bers,namely, the headstock and two cross supthe revolving body is caused torotate first at a porting members, are longitudinally adjustable tospeed higher than the critical speed oi the repermit bringing anarbitrarily selected transverse i5 silient supporting means, and thenpermitted to plane of the work into coincidence with the pivots. 15revolve freely upon ball bearing supports while a procedure essential todirect measurement of the rotative speed gradually diminishes from thecorrection required in each oi two arbitrarily above to below thecritical speed, thereby setting selected planes of the work. A secondtransverse up a maximum amplitude of oscillation of the plane of thework may be brought into coincisupporting means as critical speed ispassed dence with the pivots either bylongitudinal move- 20 through,which maximum amplitude is a directly ment of the members on the frameor by interproportionate measure of the unbalance to be changing the twoends of the work. In detail determined. Features are also disclosedwhich arrangement this machine represents only one would be equallyapplicable to a machine of conof many possible constructions, and thespecinc stant speed power driven type. reference to the relativelocation of parts is here 25 Among the novel features of this inventionare: given for reference purposes only, or to signify A resilientpivotal mounting of the supporting apreferred construction. means'whichis adiustable as to the supporting In the several views of the drawingslike charstrength o1' the resilient members in accordance acters havebeen used to designate identical with the weight o1' the work and thenatural parts. 30 period or critical speed oi' oscillation, besidesFigure 1 is a front elevation oi the complete vbeing frictionless in itsoscillation save for the machine empty oi' work. internal hysteresis oi'springs and for atmos- Figure 2 is a plan view of the complete machinepheric resistance. A ily wheel and universally showing a crankshaft inplace as work to bel adjustable balance weight are carried by thesupbalanced.

porting means, to which the work may be ad- Figure 3 is an elevationtaken from the lei't justably aligned, and which by its rotative inofFigure 1. ertia controls the rate at which the revolving Figure 4 is asection taken on the line AA of work passes through the critical speed.Friction- Figure 2.

40 less flexible means for connecting without con- Fgure5 is a sectionand partial elevation taken 40 straint the work, with a source ofdriving power on the line BB oi' Figure 4. or flywheel control,including revolving parts Figure 6 is an elevation and partial sectionthrough which quantities o1. counter-balance may taken 0n the line CC ofFigure 4. be applied. 'I'hese revolving parts are installed Figure 7 isapartial section shown in perspec- UNITED STATES PATENT OFFICE on themachine for the application and positiontive taken on the line DD oiFigure 2. 45 ing of. counter-balance equivalent to the correc- Figure 8is a rear quarter perspective taken tion determined for the work.Frictionless adfrom position EE oi' Figure 1.

Justable means for actuating an amplitude indi- Referring to Figure 1, Iis the base on which is cator from the oscillations of the supportingthe supporting member le. Clamped to the supmeans are provided. Aretaining lock and reporting member, I, in transverse alignment, are 50leasing device for locking the supporting means two plate spring pivots2, to the upper edge oi' at the neutral position of rest and releasingsame which are clamped supporting members I* which without jar or falsedisturbance when amplicarry the rectangular frame 3. The right extudesoi' oscillation are to be observed. tremity oi' frame 3 is adjustablyconnected by a In general arrangement the machine consists screw t to agooseneck spring 5 carried on the 55 iree end of a cantilever spring 6.The left end of the spring I is attached to the left supporting memberIh and at an intermediate lpoint the spring 3 is secured by clamp blocks1 and 1 to a slide l, the free length of the spring 3 which liesadjustable by a slide l. arrangement the natural vibratory period, orcritical speed, of frame 3 may be varied at will, since the sh'orter thefree length of the spring 3, the more rapid will be the vibratory periodof the frame 3, and the longer the free length of the spring 3 the moreslow will be the vibratory period or critical speed. The adjustabilltyof critical speed is of particular advantage whenlchanging the set-up ofthe machine to a piece f work of different weight. for an increase inweight of the work overhanging the pivots will cause a slower criticalspeed, so that without this adjustment a different spring would berequired for every setup, in order to arrive at the same critical speed.Also the required adjustment to increase a critical speed thus reducedby an addition of weight will be a shortening of the cantilever lengthof spring B. which at the same timewill increase the strength of thespring tc support the additional weight. The machine is, therefore,adapted to a wide variety in the weight of work. Since the total supportof frame 3 is effected through springs 2, 5 and 6, which have all jointssecurely clamped and 'no mechanically journalled connection, there is nofrictional resistance to oscillationl other than atmospheric resistance,and internal hysteresis of the springs. The latter hysteresis of springsis smaller than the friction of any known mechanical pivot or journal,and the sensitiveness of the machine to small amounts of unbalance isaccordingly very great, in view also o'f the light weight constructionof the oscillating frame which is designed for necessary mechanicalstrength only, and not for rigid alignment of par. The elimination offriction in the oscillation of the frame is essential inA order thatamplitudes of oscillation may be directly proportionate measures ofamounts of unbalance.

longitudinally adjustable at the left end of the frame 3 is a headstockframe 3 which carries a ywheel III supported in ball bearing journals II, shown in Figure 4. Rtatably mounted on the hub of flywheel I0 is acorrection disk I2 which is locked against relative movement upon III bymeans of the threaded clamping wheel I3. The web of disk I2 is slottedradially to receive the -adjustable weight I4, vernier, block I5 andclamping knob I3.. the combined weight of which is carefullystandardized so that movement of this assembly a known radial distancewill correspond to a known quantity of unbalance. For example, a weightof ten ounces moved one inch represents a change in balance. or aquantity of unbalance equal to ten ounce-inches.

InFigureareseenaclamping knob Nanda vernier block Il, which is movableradially adjacent to graduated scale I2.. Block I6 carries graduationsforming ten equal divisions having a total combined length equal to ninedivisions on scale I2, thus aifording vernier readings of positionwithin one-tenth of the smallest divisions on With the weight set at theinner positionorseroreading, disk I2isinperfectindependent balance andcan be turned to any angular position with respect to flywheel Ilwithout up- Flywheel Il,togetherwith all other members mounted torevolve on jour- `will permit, and is nals I I is also in perfectbalance. Radial adjustment of weight assembly, I4, I5, I8 combined withangular adjustment of disk I2 permits the application of balancecorrections of any desired magnitude or angular pomtion.Shouldthemagnitude 5 oi' the desired correction be greater thanpermitted by the outer extremity of the adjusting slot, two threadedopenings I2b are provided, in which may be inserted equal known weightspermitting assembly I4, I3, I3 to be set back to zero, and thenceproceeding by addition as with the rider on a scale beam after addingweights to the pan.

The periphery of ywheel III is graduated with angular divisionsreferring to an index point on the rim of the disk I2, so that anydesired angular position for disk I2 may be readily set off.

For purposes of setting the revolving work into motion, as for exampleby hand or power friction applied to flywheel Ill, and in order that 29the inertia of said flywheel may be transmitted to the work, saidflywheel is rigidly mounted on tubular shaft I1 journaled in ballbearings Il and connection is made to the work as follows. At the leftend of the shaft I1 is a tapered soft collet 25 I8 which by means of nutI3 engages the internal shaft 20, passing through the tubular shaft I1.

The right hand end ofthe shaft 20 is engaged by means of threaded collet2l and hub 22 to 'a cup 23, the split sides of which engage the work 30by means of clamp collar 24, which is locked by screw 25. Shaft 20 ispurposely made slender and of considerable length in order to be asflexible as possible, being preferably of spring material so as topermit slight flexure between the 3;, work and the headstcck withoutrestraint upon the bearings. In order to prevent torsional vibrationbetween the work and the flywheel, which otherwise would occur throughthe elasticity of the shaft 20, a tangential driver 23 is engaged 4;, toclamp the collar 24 by means of a grooved washer 26 and a nut 21, and atthe other end is engaged by means of beveled washers 30 and a nut 3l topin 32 set in the face plate 33, which is in turn rigidly mounted on theshaft 4;, I1. The parts upon the pin 32 are counterbalanced by the pin34, and a collar 24 is perfectly balanced with the driver 23 engaged.Driver 2l is also as slender and exible as requirements preferably ofspring material. 50

The work is carried upon four ball bearing rollers 35, each cf which hasindependent vertical adjustment by means of a screw 36 and a nut 31,being guided by a key 33 and locked by clamp screws 33 to the supports40, which are separately 55 adjustable on cross members 4 I 'I'he fourscrews 36 are adjusted to place the rotative axis of the work inalignment with the rotative axis of the shaft I1 when the frame 3 is atrest. Internal shaft 20 and a. driver 2l are then engaged wlthco outstrain so that the only forces acting upon the frame 3 are the forces ofunbalance in the revolving bodies.

In order that the maximum amplitude oir oscillations taken as criticalspeed is passed through c5 may be a directly proportionate measure ofthe amount of unbalance, it is necessary that the frame 3 be lockedagainst oscillation during the time that the revolving parts are set Inmotion at a speed above critical speed, and that the frame 3 bethereupon released from a truly neutral position of rest and permittedto act without interference or false jar under the disturbing forces ofunbalance only. A gradually redingtouchofthehandorilngerwiilservethepurpose but mechanism means for effecting the result are shown in Figure7. Upon the left cross member of the frame l is a forked member I2adjustably locked in position by a clamp bolt or bolts 49. Upon thetransverse faces of th depending forked portions of 42 are mounted`lfour spring members M so attached to I! at their upper ends that thelower ends diverge from a position of contact with said faces unlessforced into contact by the application of a transverse pressure.Parallel with said member of the frame 3 and passing between the forkedportions of 42 is a shaft I5 upon which are screw threads I8 and Ilrespectively of right hand and left hand pitch. Engaging these threadsrespectively are threaded clamp Jaws Il and 49, which are slidablyguided on a pin 50. A clockwise turning of shaft I5 will therefore causethe blocks Il and 49 to move toward each other, while a counterclockwise turning of shaft 45 will cause a reversed movement.

In order that frame I may oscillate without friction jaws 48 and 49 mustseparate sumciently to remain completely out of contact with springs u,collar 5I being employed to limit excessive movement in this direction,and to guide the operator in obtaining the correct position of freedom.When there is no disturbing force acting upon the frame 3, any residualof vibratory oscillation may be readily damped out with this device bybringing jaws 49 and I9 into contact with springs 44 'and graduallyreceding to a position of no contact. The gradually diminishing frictionbetween the contacting surfaces will thus bring frame 9 to rest at theneutral position. In order that this process may be most eil'ective, itis desirable that the contacting faces of springs M and jaws 49 and 49be well smoothed and highly polished. Frame 3 is locked by bringing jaws49 and 49 forcibly together to clamp members 44 and l2 as in a vise.Shaft l5 is actuated by a lever 59 seen in Figures 1, 2 and 3.

proportionality of observed amplitudes of oscillation is of primeimportance in the process employed on this machine. and since theobtaining of proportionality between such amplitudes and quantities ofimbalance necessitates the absence or a very great reduction offrictional resistance to oscillation, an amplitude indicator is requiredwhich consumes the smallest possible energy in friction, and at the sametime gives visual indications or readings of suitable proportionate sizefor numerical interpretation of the smallest quantities to be dealt within practice. Likewise the largest amplitudes to be encountered must bewithin the range of observable readings on the indicator, and anadjustment of the indicator permitting a variation of the scale of thereadings will be useful in that the movement of the indicator hand whenobserving large amplitudes of oscillation need not be so great in linearvelocity as to render observations both diilicult and inaccurate.

Figure 8 shows the mounting of an indicator of the type employed bymachinists for observing the accuracy of metal parts: such an indicator,if possessing small frictional resistance, being adapted to the purposebecause of the small necessary motion of the actuating parts andconsequent small energy of friction. By the mounting here shown, theindicator is placed in a position convenient to careful observation bythe operator, and is provided with an adjustment permitting variation ofthe scale of readings. 54 is a column supported on pedestal i of thebase and carrying head 55. Clamped horizontally to 55 is a leaf spring58 which when free is so upwardly curved that upon being drawn down bythe wire 51 and attached to ythe frame I at its neutral position ofrest, it has a position 5 and contour when so restrained, which issubstantially horizontal and straight. Vertical oscillation of the frame9 will then be accompanied by a proportionate vertical movement of allportions of the free length of the spring 59. the mag- 10 nitude of suchmovement being greatly diminished as the point considered approachesnearer the point of rigid attachment between the spring 56 and the head55. Also carried by the head 55 on the column Il is an arm 59 mounting a15 rod 59, upon which is slidably mounted a sup-- port 50 which may belocked in position by means of a thumb screw 8l. The indicator 92 ismounted upon a support 60 with its actuating ball point il resting uponthe spring 59 so that 20 oscillation of the frame 3 and spring 58 areindicated by movement of the dial hand of indicator 52, which is at theobverse side as seen in Figure 8. By virtue of substantial parallelismbetween spring 5B and rod 59, the support S0 25 may so be moved alongthe rod 59 as to vary the proportionate oscillations of the ball 63 andhence to change the scale of movement shown by the dial hand ofindicator 92. Adjustable stop collars M and 55 may be set at determinedposi- 30 tions on rod 59 representing two locations of indicator 62which may be found adapted to two varieties of work, or diil'erlng fromeach other by a predetermined ratio between the scales of movementobserved at the indicator dial hand. 35

For example, when support 80 is adjusted to the limiting position incontact with collar 6I, the movement of the dial hand on indicator 62for a given amplitude oi' oscillation of the frame 3 corresponding to agiven amount of unbalance 40 may be exactly one-tenth oi' thecorresponding movement of the dial hand when support 60 is in contactwith the collar 55. The latter position of indicator 92 is accordinglyadapted to observing small quantities of unbalance, and the former 45 toobserving large quantities of unbalance, and the proportionalrelationship between quantities of unbalance and observed amplitudes maybe readily retained numerically by proper positioning of the decimalpoint. 60

We claim as our invention:

l. In a balancing machine, a base, a support for the body to bebalanced, resilientmeans on said base mounting said support forsubstantially pivotal vibration, said resilient mounting 55 means beinglocated in a correction plane of the body to be balanced, a resilientcantilever on said base, and flexible means connecting said cantileverto said support permitting relative movement therebetween. 60

2. In a balancing machine with a pivotally mounted support for therevolving test body, a flywheel Journaled to revolve upon said supportin substantial alignment with the test body, means adapted to revolvewith said ywheel com- 65 prising a weight adjustable with respect tosaid flywheel both to known degrees of unbalance and to known angularpositions, connecting means comprising a flexible member transmittingtangential forces to interconnect said flywheel and test body, andanti-friction bearings for said body and for said flywheel.

3. In a balancing machine, a base, a support connected to said base tooscillate and to revolvably carry, a test body. means to rotate thebody, retaining means on said support, means mounted on said base forexerting pressure on said retaining means and for gradually releasingsaid pressure, and resilient frictional means interposed between saidretaining means and pressure exerting means, whereby said support may befrictionally retained against oscillation, or said friction may begradually reduced to permit said support to oscillate while said body isrotating.

4. In a balancing machine, an oscillatable support for a revolving testbody, a graduated oscillation amplitude indicator. means including africtionless element operatively connecting said indicator to saidsupport, and means for adjusting a connection relative to saidirictionless element operative to vary the ratio between the oscillatorymovements of said support and the movements shown by said'indicator.

5. In a balancing machine, an oscillatable support for a test body, agraduated oscillation amplitude indicator, means including a movable armoperatively connecting said indicator to said support, and means forvarying the operative point of connection between said arm and saidindicater eiective to vary the ratio between the oscillatory movementsof said support and the movements shown by said indicator.

6. In a balancing machine, the combination with an oscillatory supportpivoted in one of the two transverse planes selected for balancingcorrections of the revolving test body carried thereon with means formeasuring amounts of unbalance by amplitudes of oscillation, ofrevolving means on said support separate from the test bodv adapted forapplying a predetermined amount of unbalance at a predeterminedposition, thereby producing the same resultant effect on the oscillatorysupport as would the required balancing correction if applied in theother of thetwo transverse planes for balancing of the tcst body,whereby the system may revolve without oscillation of said support.

'1. A balancing machine for revolving bodies comprising an oscillatableframe having ways parallel to the rotational axis of the body, a pivotcontrolling the frame to oscillate about an axis perpendicular to therotational axis of the body, supports adjustable on said ways atopposite sides of the pivotal axis and adapted to carry a revolving testbody with a selected transverse correction plane of the test bodycontaining the pivotal axis; a head-stock also adjustable on said waysand carrying revolving parts coaxially with the test body and connectedthereto, which are adaped for applying a determined amount of imbalanceand for locating said unbalance at a determined angle with respect tothe revolving test body.

8. In a balancing machine the combination with an oscillatory frameadapted to rotatably support a test body, said frame being pivotallyrestrained to oscillate transversely to the axis of the rotatable testbody, of means revolving coaxlally with the test body for applying andlocating balancing corrections and disposed at the opposite side of thepivotal support from the selected plane of the test body for which acorrection is being determined.

9. In a balancing machine, a base, a support for the body to bebalanced, means on said base mounting said support for substantiallypivotal vibration, a resilient cantilever on said base, flexible meansvconnected to said cantilever. and ad- Justabie means connecting saidflexible means and said support.

l0. In a balancing machine for revolving bodies, the combination with abed, a support for the body to be balanced mounted to oscillate on thebed 5 and provided with means by which said body may be carried whilebeing free to revolve, means on said support arranged to be connected tothe body to be operated, said means being adapted to have power appliedthereto for revolving said body,10 means to lock said support againstoscillation while said body is being revolved and to release saidsupport after the body to be tested has been set in motion, thereafterpermitting the body to revolve and the support to oscillate without me-1;, chanical interference.

11. A balancing machine having a support for a revolving test body, thesaid support being mounted to oscillate about a pivot. a spring meansconnected to the support in a manner to influence 2o oscillationsthereof, means for indicating the oscillatory positions of said support.and adjustable means connected to the spring means to cause said supportto assume a desired neutral position when under static load, asregistered by 2.', said indicating means.

12. In a balancing machine awork support adapted to oscillate, acantilever spring having its free end connected to the work support insuch manner that the natural vibratory period thereof may be varied byvarying the effective length oi' the cantilever portion of the spring,the entire support and connection of the work support with thecantilever spring being eilected by means whereby there is substantiallyno frictional resistance to oscillation, means arranged upon the worksupport for rotating work and means adjustably connecting the worksupport and spring.

13. A balancing machine for revolving bodies having the combination of asupport for the body, 40 mountings for said support permitting vibrationsubstantially pivotal, a spring connected to the support and controllingthe natural period of free vibration, locking means movable relativelyto the support and permitting said support to be released 4:, or lockedagainst vibration, and resilient friction members engageable with themovement of said locking means, whereby the locking means may bereleased, accompanied by gradual reduction of friction. Y

14. In a balancing machine, a base having a pivot member mountedthereon, a support revolubly'carrying the body to be balanced andmounted for vibration about the axis of said pivot, flexible meansconnected to said support and spaced from said pivot, a resilientcantilever operatively connected to said flexible means for controllingvibration of said support, and means for adjusting the stiffness of saidcantilever for regulating the natural frequency of vibration of saidsupport.

15. In a balancing machine with a support for the revolving body,clamping means having surfaces parallel to the natural direction o!vibration of the support, a retaining member secured to the support,means to exert or release a pressure between said clamping surfaces andretaining member, and resilient means interposed therebetween, wherebythe frictional damping to vibration may be gradually diminished as saidclamping means are released.

16. In a balancing machine with an oscillatory support for the revolvingbody, clamping means having surfaces parallel to the natural directionof oscillation o! said support, resilient means secured to saidsupport'and extending between said 75 clamping surfaces, and means toexert or release a pressure between said clamping surfaces and resilientmeans, whereby the frictional damping to vibration may be graduallydiminished as said t clamping means are released.

17. In a balancing machine having a resiliently mounted frame adapted tosupport a rotating body in a plurality of bearings, a spring comprisinga portion of said resilient mounting, means for adjusting said spring asto the characteristic ratio of force increment to deflection incrementbetween a polntof fixed support and the point of attachment ofsaid'spring to the said supporting means, operating means comprising ashaft mounted on said frame to revolve in substantial alignment with therotating body, and exible means transmitting' tangential forces betweensaid shaft and body to revolve synchronously.

18. In a machine for balancing revolving bodies upon a vibratable frame,a flexible shaft connected to the revolving body in substantial axialalignment therewith, a hollow shaft iournaled on said frame, said hollowshaft surrounding said flexible shaft and being connected thereto nearthe opposite end from said body, and means ad- Justable with respect tobalance canied hollow shaft.

19. In a machine for balancing revolving bodies upon a frame whichoscillates about a reference center contained in a transverse planeintersecting the revolving body near one end thereof, a flexible shaftconnected to said end of the body in substantial axial alignmenttherewith, a hollow shaft journaled on said frame, said hollow shaftsurrounding said flexible shaft and being on said connected thereto nearthe opposite end from said body, and means adjustable with respect to.balance carried on said hollow shaft.

20. In a balancing machine, the combination with a support mounted tooscillate about a pivot in one of two transverse planes selected forbalancing corrections on the revolving test body carried thereon, ofrevolving means on said support and iiexibly connected to the test bodyfor applying a determinate amount of unbalance at a determinateposition, thereby to produce the same resultant effect on theoscillation of said support as would be produced by the requiredbalancing correction if applied in the other of the two transverseplanes selected for balancing the revolving test body.

2l. In a machine for balancing revolving bodies having a support mountedto oscillate about a pivotcontained in a transverse plane intersectingthe body. a flexible shaft connected coaxially to the body, a hollowshaft journaled on said support and enclosing said flexible shaft andconnected thereto near the opposite end from the body, and means mountedon said hollow shaft for applying and locating balancing corrections foroffsetting the unbalance to be corrected in a transverse plane of thebody disposed at the opposite side of said pivot.

22. In a .balancing machine, a base having a pivot xed thereon, a framemounted to oscillate about said pivot, supports on said frame 5 uponopposite sides of said pivot for carrying a rotatable test body. andmeans to adjust said supports and test body with respect to said pivotin a direction parallel to the rotational axis of said test body,whereby an arbitrarily selected correction planemay be made to containsaid pivot.

23. In a balancing machine, a frame for rotatably supporting a test bodyand mounted for vibration about a reference center contained in a planetransversely intersecting the test body and intended to receive abalancing correction,

a headstock with a revoluble shaft having means for applying balancingcorrections and mounted on said frame co-axially with the test body. andexible means for applying tangential forces betven said shaft and testbody whereby said body may be revolved by said shaft.

24. In a balancing machine, a frame for rotatably supporting a test bodyand mounted for vibration about a pivot, a headstock with a revolubleshaft having means for applying baiancing correction and mounted on saidframe coaxially with the test body, and flexible means for applyingtangential forces between said shaft and said test body whereby saidbody may be revolved by said shaft.

25. In a balancing machine, a frame adapted to oscillate about a pivot,supports on said frame upon opposite sides of said pivot for carrying arotatable test body with a selected transverse correction plane of thebody containing said pivot. and a headstock carried by said frame andcomprising revoluble means for applying unbalance of any desired amountand angular position. said 4o headstock and one of said supports beingadjustable on said frame with respect to said pivot in a directionparallel to the axis of rotation of the' test body.

26. In a balancing machine, an oscillatable support. a test body mountedfor rotation on said support, means adapted intermittently to revolvefreely or to have power applied thereto for rotating said test body.pressure means for applying friction to said support to prevent oscil-5o lation while said power is being applied, and means for graduallydecreasing the friction produced by said pressure means on said supportto permit said support to oscillate.

AMOS F. MOYER.

PRECISION BALANCING MACHINE COM- PANY, Assignee of Francis T. McDonough,Deceased, Y

By WILLIAM C. TUI'TS. President.

